North Korean soldiers briefly crossed the border inside the DMZ for the third time in weeks, prompting South Korean troops to fire warning shots, the South’s Joint Chiefs of Staff said Friday. The North’s soldiers are conducting construction work at the frontline, as seen in this photo provided by the South Korean military on June 18. Photo courtesy of Republic of Korea Defense Ministry

“Several North Korean soldiers working within the DMZ on the central frontlines crossed the [military demarcation line] and headed back north after our military made warning broadcasts and fired warning shots,” the JCS said.

The incursion was the third crossing by the North in recent weeks, with similar incidents taking place on Tuesday and June 9.

JCS officials said the crossings appear unintentional, as the North has been ramping up activity in frontline areas of the DMZ since withdrawing from an inter-Korean military agreement in November.

North Korean soldiers have been observed clearing land, laying mines, reinforcing tactical roads and installing structures that appear to be anti-tank barriers at several locations in the DMZ.

Earlier this week, the JCS said that the work has been carrying on despite “numerous casualties” caused by landmine explosions.

Tensions remain high near the DMZ, with North Korea sending trash-filled balloons across the border earlier this month and the South resuming anti-Pyongyang loudspeaker broadcasts.

An activist group of North Korean defectors said Friday that it floated 20 balloons carrying 300,000 anti-Pyongyang leaflets, USB drives containing South Korean media and U.S. dollars across the border.

The group, Fighters for a Free North Korea, said it sent the balloons on Thursday night from the border city of Paju, according to local media reports.

North Korea has reacted with fury in the past to defectors sending balloons across the border. In June 2020, Pyongyang severed all communications with Seoul and blew up an inter-Korean liaison office over what it called South Korea’s failure to rein in the defectors.

On Friday, Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, issued a statement condemning the latest balloon launch by “disgusting defectors” and warning of possible retaliation.

“The border area of the DPRK was again littered with dirty wastepaper and things,” Kim said in the statement, which was carried by state-run Korean Central News Agency.

The Democratic People’s Republic of Korea is the official name of North Korea.

“It is natural that there would be [some] trouble to happen as they did again what they had been urged not to do,” Kim said.